Email Troubleshooting
Reliable email deliverability is one of the most common challenges when running your own mail server. This section gives you an overview of the most frequent causes and how to resolve them.
Why Do Emails End Up in Spam?
Major email providers like Gmail, Outlook, or Yahoo automatically check every incoming email against a set of criteria. If these are not met, emails are flagged as spam or rejected outright — regardless of their content. The most common causes are:
Missing or incorrect server identity
The PTR record and SMTP HELO do not match, or both point to a generic hostname provided by the hosting company.
Missing email authentication
SPF, DKIM, or DMARC are not configured — the recipient cannot verify that the email genuinely originates from your domain.
IP address on a blacklist
Your server's IP address appears on one or more public blacklists — emails are automatically rejected by receiving mail servers.
Compromised server or account
An attacker is using your server or a weak password to send spam at scale, damaging your sending reputation.
Email Authentication Checklist
For maximum deliverability, all of the following should be correctly configured. Missing entries are the most common cause of spam problems:
| Record | Purpose | Priority |
|---|---|---|
| PTR | Maps your IP address to a hostname — the first check performed by many mail servers | Required |
| HELO | The name your mail server uses to identify itself — must match the PTR record | Required |
| SPF | Defines which servers are authorized to send emails on behalf of your domain | Required |
| DKIM | Adds a cryptographic signature to outgoing emails — proves authenticity and integrity | Recommended |
| DMARC | Defines what happens to emails that fail SPF or DKIM checks | Recommended |
Since 2024, Google and Yahoo require DKIM and DMARC for bulk senders. For all other domains, both records are now strongly recommended regardless of sending volume.
Detailed Guides
Select one of the following guides for step-by-step instructions:
Still having email delivery issues?
For server infrastructure related problems, our support team is available via the PowerPanel ticket system.